Electromagnetic compass.



L. D. J. A. DUNOYER.

ELECTROMAGNETIC COMPASS. APPLICATION FILED 1mm, 1901.

989,134, I 4 Patented Apr. 11,1911.

3 SHEETS-BHBBT 1 -4- 1 4 J H I 1 .1 1 141' //vv/v TOR.-

L. D. J. A. DUNOYER. ELECTROMAGNETIC COMPASS. APPLICATION FILED MAB.5,1907.

Patented Apr. 11, 1911.

3 SHEETS-SHEET 2.

INVENTORI WITNESSES:

fla MW L. D. J. A. DUNOYER.

ELECTROMAGNETIC COMPASS. APPLIOATION FILED Mum, 1907.

3 SHEETS-SHEET 3.

WITNESSES M/VE/VTOR:

Patented Apr. 11, 1911.

UNITED sTArnsggrENtr OFFICE.

LOUIS DOMINIQUE JOSEPH ARMANI) DUNOYEB, OF VERSAILLES, FRANCE.

ELECTROMAGNETIC COMPASS.

I Specification of Letters Patent. Patented Apr, 11, 1911.

Application filed March '5, 1907. Serial No. 360,770.

' To all whom it may concern:

magnetic field.

.this deflection which determines the angle inclosed by the longitudinalaxis of the ship withthe magnetic meridian.

This apparatus will be particularly useful for obviating the disturbingeffect upon the needle compass: 1. Of the masses of iron orsteelsurrounding the deck houses or central :stations on board ship. 9..Of the considerable vibration which affects the magnetized needle intorpedo boats and motor boats. The rotary frame may in fact be placed ata spot (for instance. on a mast) 1 where perfeet compensation can bemade readily and i with certainty.

- An apparatus. embodying the invention is shown in the accompanyingdrawings, in

. gram. showing shown diagrammatically in Fig.5. 1

Figure 1 in elevation, and in Fig. 2 in plan. Figs. 3 and 4 arediagrammatic representations of tables containing previously determinedvalues of-the coetlicicntsof the apparatus and theangles of deviation..Figs.

5, 6, and 7 refer to a modification. Fig. .5 is. an elevation showing.the general arrange ment ofthe apparatus. Fig. (his an axial sectionthrough, the .frame and the. disks.

Fig. 7 is a plan thereof. Fig. 8 is a dia-. themanner. in which thedeviation is to beread off .from the appan ratus of Fig.6. Fig. 9 is aseparate view of the receiving and indicating apparatus The device shownin Figs. 1 and 2 is composed of a, preferably circular, frame A, of

insulating materialcor of a metallic substance in which slots aresuitably made so .as'to. prevent the generation .of Foucault currents.Upon this frame is wound insulated copper wire .13. 'The frame iscapable of rotating on a vertical axle C situated "in its plane andpassing through its center,

this motion being imparted to it by any desired means. i

At right anglesto the axle and rigidly fixed to it there is provided ahorizontal disk D of insulating material. The circumference of the diskis covered with a metal band E cut in two places a a by very fine cutssituated at the ends of that diameter of the disk D which isperpendicular to the plane of the frame A. 'Each of the two conductingsemi-peripheries thus formed, is connected to one, end of the wire thatis wound on the frame. periphery there rub several pairs of brushes H H;each pair is located at the ends of one and the same diameter. These twopairs of brushes are indispensable. If greater accuracy is desiredaccording to the sensitiveness of the galvanoineter employed,other pairsof brushes may be utilized situated at the ends .of the intermediatediameters. There are always two pairs situated at the ends'of twodiameters located at right angles to each other. Each of these pairs ofbrushes is connected by means of two insulated wires H H to a suitablemeasuring instrument such as a galvanometer of any suitable type. v

The amount of the galvanometric deflection will indicate the magneticdeviation of the ship.

The rotary frame is tobe placed in some convenient spot on the shipwhere the magnetic compensation of the masses of iron and steelconstituting it may be effected in an eflicient manner; an especiallysuitable spot is on a'mast.

No part of the apparatus should be of iron.

To use the apparatus, the frame is caused to rotate in a uniform manner,and by means of a multipolar switch the two brushes of one and the samepair are connected to the two terminals of the galvanometer; and thedeviation 8 is read off the latter.

.ssuming that use is made at first of the pair of brushes fixed at theends of the diametcr'per endicularto the longitudinal axis of the ship,and let a. be the magnetic deviation of the ship that is to say, theangle inclosed by its axis with the magnetic meridian then we have tan.8=A'. sin. It now by means of the multipolar switch,

On this conducting use he made of the-pair of brushes fixed to the endsof the diameter parallel to the axis of the ship, the deviation 8 isgiven by the equation tan. 8:A. cos. a.

We have then tan? S-l-tan? 8:A2.

These two values thus serve to determine the coeflicient'A- It is onlynecessary to determine those two .values from time to time forthepurpose of determining the value of the coefficient A which varies withthe longi-,

tude the latitude and the rotation of the frame. I

In practice a table in double entry of the velocity of the values of Awill be prepared beforehand,by arranging the values of the horizontalcom-, ponent H of the earths field in vertical columns and arranging thevalues N of the number of revolutions per second-in horizontal lines.This table having been prepared, a second table 'is then prepared (seegalvanometer.

the diagram Fig. 3) showing the values of A in a vertical column at theleft as indicated and those of a. in a horizontal line at the top asindicated at 1. In the compart-' ments 4: 4 of this table will be foundthe values of 8 and of 8'. Finally a third table (see the diagram Fig.4) contains in the left hand column 4, the values of 8. and in the topline 4 the values of 8, and in these compartments 1 the correspondingvalues of'A and of 0,. These two last tables are infront of the eyes ofthe steersman. They allow of solving the following two practicalproblems 1. To follo'w a give-n course-This consists in giving a atevery moment. A is determined from time toiime by the methodhereinbefore described. The second table alone thus gives the. deviation8 which the steersman must keep in the galvanometer by suitablesteering.

%. To take a gi ven course.A and 8 of the given course are determined;this gives a from the third table. It is necessary therefore to Veer bythe angles u from the magneticdeviati'on a at the time. The second tableis then inspected alon the topline to find the column correspondlng tothe 'angle a+u,' the compartment thus found gives the deflection 8 whichmust be imparted to the With the object of obviating the twomeasurements of 8 as hereinabove stated, and also of dispensing with theuse of the two tables, the apparatus may, be completed in the followingmanner :It then comprises two windings on the same frame, and two pairsof half rings, these pairs being each connected to a galvanometerthrough the medium of suitable brushes and con- (luctors. Upon themirror of each galvanometer there will be reflected respectively tworelatively perpendicular lines which form on a dull glassplate or othersurface images whose point of intersection serves for obtaining thedeviation as hereinafter described.

The apparatus consists of a frame A, preferably CIICHla-I," in which areformed two parallel grooves capable of receiving two similar windingsBand B. On the pivotal axis C C of the frame there are fixed twodisks 1) and D of insulating material,

on the circumference of which there are arloid or any other analogousselnl-tran'sparent substance) an image f of a fixed wire F parallel toits axis Likewise, the mirror m 'ofthe galvanometer G gives an image fof a straight line F parallel to its axis. If

the frame A of the transmitter be caused to rotate, these images 7 and fwhich ,are perpendicular to each other, will move over the dull glassplate P on which there is engraved a series of radius vectors spacedsuitably apart in the form .of' a marmers compass card divided into 360degrees; each radius vector bein marked with a sign such as N, NE, &c.all but one being omitted from Fig. Qfor the sake of clearness). Theradius vector on which the crossing point of the two perpendicularimages f and 7" stops, indicates the magnetic deviation of the ship. Infact, if u. be this. magnetic deviation, the diagram (Fig. 8) show thatZ=A sin. d Z=A cos. a

the angle a. being indicated at the point 1. Z and Z representing thedisplacement of the images which is proportionate to the de fiection ofthe galvanometers, and A being a coefiicient which varies with thelongitude, the latitude and the velocity of the rotation of the frame.

From the two preceding equations, there results %=tan.a.

If 03 and OX represent the two images f and f, and OM the radius vectorupon which the crossing points of said images lie I then the angle M03is equal to the angle; the magnetic deviation of the ship. Thus in thiscase, the magnetic deviation is obtained here by simply reading the sameon the indicated radius vector on the'plate P without the use of tables,whereas in the first arrangement the coetiicient A rendered the use oftables necessary. Furthermore, by causing the dull-glass plate to rotatein a suitable direction through an angle equal to the declination of thelocality of observation, the geographical deviation will be obtained.Finally,--the receivin apparatus formed of two galvanometers and Ghavlng a movable frame and having their',axes perpendicular to eachother, and having mirrors that form on a dull glass plate P the imagesof two wires F and F or two incandescent filaments at right angles toeach other, may serve in all cases where it is desired to measure theproportion between the intensities of two currents, because theseintensities are proportionate to Z and Z. For this purpose it will besuiiicient to graduate the radius vectors in values of tan, a.

Applicant reserves the right of modifying the dimensions or the detailsof this apparatus for the purpose of applying it to the measuring of theproportion between the intensities of two currents. Fig. 9 is a separate view of such apparatus. The galvanometers G and G are connected inany desired way with the'circuits of the two currents in question, andthey throw upon the plate or screen P images f, f of a pair of lines Fand F, shifting the positions of said lines according to the intensitiesof the two currents, so that the point of intersection of said two lineswill fall upon different'radii upon the screen, according to therelative intensities of the two currents in question. This mechanismserves the same purpose whether used in connection with the otherelements of the electromagnetic compass described or not.

Claims.

1. A compass for determining magnetic deviation, including incombination a coil adapted to be rotated in a magnetic field and inwhich induced currents are generated, a

vcurrent collecting ring with gaps at diametrically opposite points,electrical connections between said coil and ring a galvanometer, andbrushes connecting said coil through said ring to said galvanometer tocause the latter to indicate the intensities of said currents.

2. A compass for determining magnetic deviation, including incombination an armature frame carrying at least one winding and adaptedto receive a uniform rotary motion about a vertical axis, a pair of halfrings and means for connecting them for rotation with said frame, atleast two pairs of brushes contacting with said half rings and locatedon diameters at right angles to each other, one of these diameters beingada ted to be set parallel to the longitudinal axis of a ship, and theother at right angles thereto,

a galvanometer, wires H and H for connecting said pairs of, brushesalternately with said galvanometer, and means controlled by thegalvanometer for indicating the angle between the axis of the ship andthe magnetic meridian.

3. A compass for finding magnetic deviations, including in combination aframe, a pair of windings carried thereon, separate pairs of half ringsconnected one pair to each of said windings, pairs of brushes for eachof said pairs of half rings and adapted to be located on diameters onein the direction of the ship and another at right-angles thereto,galvanometers subject to simultaneous deflection, means connecting oneof said galvanometers to each of said pairs of brushes, and anindicating apparatus controlled by said galvanometers for indicating thedeviations of the direction of the ship.

4. An indicating apparatus includin two galvanometers having mirrorsrotatab ie on horizontal axes perpendicular to each other, two wiresarranged perpendicularly to each other and reflected by the respectivemirrors of the galvanometers, a screen upon which said lines arereflected and upon which the position of the intersection of the linei11- dieates the relative positions of the mirrors, said screen beinggraduated in the manner of a mariners compass.

In witness whereof, I have hereunto signed my name this 22d day ofFebruary 1907, in the presence of two subscribing witnesses.

LOUIS DOMINIQUE JOSEPH ARMANI) DUNOYER. Witnesses:

ltL-uzcrn ARMENGAUD, J eune, Hmmanno DE Soro.

